TOKYO (Reuters) - Tokyo Electric Power (Tepco), the operator of Japan's wrecked Fukushima nuclear plant, may have found nuclear fuel debris below the damaged No. 3 reactor, one of three that had meltdowns in the 2011 disaster, Kyodo News reported on Friday.

Tepco detected black-colored material that dangled like icicles that could be nuclear debris near the bottom of the reactor's pressure vessel that contained the fuel rods, the report said, citing unnamed sources.

Finding the highly radioactive melted fuel rods may pave the way for Tepco to develop methods to remove the melted fuel.

Tepco launched its first attempt to probe the inside of the No. 3 reactor using a submersible robot on Wednesday, the company said in an e-mail on Thursday. The company plans to continue its probe until Saturday.

A Tepco spokesman said on Friday the company has yet to analyze the findings from the probe.

The company in January spotted possible nuclear fuel debris below the damaged No. 2 reactor at the plant.

In the world's worst nuclear calamity since Chernobyl in 1986, three reactors at the Fukushima Daiichi plant melted down after a magnitude 9 earthquake struck off the coast of Japan in March 2011, triggering a tsunami that devastated a large area and killed more than 15,000 people.

The utility has been developing robots that can swim under water and negotiate obstacles in damaged tunnels and piping to search for the melted fuel rods.